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    Subject[PATCH 5.17 383/772] Bluetooth: fix dangling sco_conn and use-after-free in sco_sock_timeout
    Date
    From: Ying Hsu <yinghsu@chromium.org>

    [ Upstream commit 7aa1e7d15f8a5b65f67bacb100d8fc033b21efa2 ]

    Connecting the same socket twice consecutively in sco_sock_connect()
    could lead to a race condition where two sco_conn objects are created
    but only one is associated with the socket. If the socket is closed
    before the SCO connection is established, the timer associated with the
    dangling sco_conn object won't be canceled. As the sock object is being
    freed, the use-after-free problem happens when the timer callback
    function sco_sock_timeout() accesses the socket. Here's the call trace:

    dump_stack+0x107/0x163
    ? refcount_inc+0x1c/
    print_address_description.constprop.0+0x1c/0x47e
    ? refcount_inc+0x1c/0x7b
    kasan_report+0x13a/0x173
    ? refcount_inc+0x1c/0x7b
    check_memory_region+0x132/0x139
    refcount_inc+0x1c/0x7b
    sco_sock_timeout+0xb2/0x1ba
    process_one_work+0x739/0xbd1
    ? cancel_delayed_work+0x13f/0x13f
    ? __raw_spin_lock_init+0xf0/0xf0
    ? to_kthread+0x59/0x85
    worker_thread+0x593/0x70e
    kthread+0x346/0x35a
    ? drain_workqueue+0x31a/0x31a
    ? kthread_bind+0x4b/0x4b
    ret_from_fork+0x1f/0x30

    Link: https://syzkaller.appspot.com/bug?extid=2bef95d3ab4daa10155b
    Reported-by: syzbot+2bef95d3ab4daa10155b@syzkaller.appspotmail.com
    Fixes: e1dee2c1de2b ("Bluetooth: fix repeated calls to sco_sock_kill")
    Signed-off-by: Ying Hsu <yinghsu@chromium.org>
    Reviewed-by: Joseph Hwang <josephsih@chromium.org>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/bluetooth/sco.c | 21 +++++++++++++--------
    1 file changed, 13 insertions(+), 8 deletions(-)

    diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
    index 2a58c7d88433..1111da4e2f2b 100644
    --- a/net/bluetooth/sco.c
    +++ b/net/bluetooth/sco.c
    @@ -574,19 +574,24 @@ static int sco_sock_connect(struct socket *sock, struct sockaddr *addr, int alen
    addr->sa_family != AF_BLUETOOTH)
    return -EINVAL;

    - if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND)
    - return -EBADFD;
    + lock_sock(sk);
    + if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) {
    + err = -EBADFD;
    + goto done;
    + }

    - if (sk->sk_type != SOCK_SEQPACKET)
    - return -EINVAL;
    + if (sk->sk_type != SOCK_SEQPACKET) {
    + err = -EINVAL;
    + goto done;
    + }

    hdev = hci_get_route(&sa->sco_bdaddr, &sco_pi(sk)->src, BDADDR_BREDR);
    - if (!hdev)
    - return -EHOSTUNREACH;
    + if (!hdev) {
    + err = -EHOSTUNREACH;
    + goto done;
    + }
    hci_dev_lock(hdev);

    - lock_sock(sk);
    -
    /* Set destination address and psm */
    bacpy(&sco_pi(sk)->dst, &sa->sco_bdaddr);

    --
    2.35.1


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